The present invention relates to a system for reducing pollutant emissions associated with the operation of a motor vehicle diesel engine. It relates more particularly to a system for assisting the regeneration of a storage/release NOx trap integrated into a diesel engine exhaust system.
As is known in the art of direct injection motor vehicle diesel engines, reducing NOx emissions by DeNOx catalytic conversion of the storage/release type is one of the technical solutions envisaged for complying with the standards relating to this type of pollution and in particular the EURO IV standards.
To this end, it has been envisaged to use a NOx trap consisting of barium sulfate, for example, and adapted to absorb NOx during operation of the engine under standard conditions.
When the trap is saturated, a transient release phase is triggered by temporarily switching the engine from its standard mode of operation using a lean mixture to a regeneration mode of operation using a rich mixture, to produce reducing agents, such as HC and CO, for example; this reduces the NOx, which are then desorbed from the trap, as in a traditional catalytic converter.